Stent

ABSTRACT

A stent ( 10 ) which may be used in the treatment of stenosis and particularly ostial stenosis. The stent ( 10 ) includes a flange member ( 15 ) which engages the surrounding wall of an ostium and anchors the stent ( 10 ) in its target vessel. A delivery system for a stent ( 10 ) is also disclosed, the delivery system including a membrane ( 109 ) or a compression member to hold an intraluminal stent ( 101 ) in a first radially compressed state until said stent ( 101 ) is delivered to a target site.

FIELD OF THE INVENTION

The present invention relates to a stent for use in occlusive diseaseand particularly occlusive disease in an area of vessel which branchesinto a second vessel.

BACKGROUND OF THE INVENTION

Occlusive diseases affecting the vasculature or other vessels arecommon. Such diseases include atherosclerosis which is characterised bya build up of plaque from cholesterol residues. The plaque build upsubsequently thickens and hardens the vessel wall to create a stenosis.The resultant narrowing of the vessel has adverse effects on blood flowthrough the vessel.

Stenotic plaques may occur at any location along a vessel wall and insome cases may present at a junction between two vessels. This iscommonly referred to as ostial stenosis or a narrowing of the opening ofa vessel. In such cases, the plaque or area of stenosis may severelycompromise the flow of blood to the “downstream” vessel.

Many vessels branch from a main vessel at approximately 90°. An exampleis the branching of the right and left renal arteries from the abdominalaorta. Ostial stenosis may occur at the junction between the aorta andthe renal artery and may predispose the patient to atheroembolisation ofthe visceral and peripheral vascular beds in addition to impairing bloodflow to the kidney.

Current medical practices employ both invasive and non-invasiveprocedures to address stenosis including ostial stenosis. While thedisease may be medically treated, in severe cases surgical interventionmay be required. The latter includes both balloon angioplasty to breakup the stenotic plaque and the delivery of an intraluminal stent tobridge the stenotic lesion.

While both procedures are commonly used, the incidence of re-stenosis inpatients treated by balloon angioplasty Is unacceptably high at anestimated 40% of cases. Bridging of the stenotic lesion with a stentsignificantly reduces the incidence of re-stenosis.

Conventional stents may be inserted percutaneously through a distal andconnecting vessel to that in which the stent is to be used. For example,the device may be inserted through the femoral artery in a catheter,where the device is intended to be used in the treatment of a stenoticlesion. Upon release of the device from the catheter it may expand to adesirable size, and may extend above and below the lesion therebybridging that lesion.

The delivery of a stent to an ostial stenosis is a difficult procedure.In the case of stenosis at the opening or ostium of the renal arteries,in order to bridge the stenosis, the stent is required to project around1-2 mm into the aorta. As the majority of stents are a simple tubularmesh structure, they may shift from the desired position during theprocedure. In such an event, the stent will either end up positioned toofar into the renal artery or projecting too far into the aorta. Similardifficulties are experienced with the placement of a stent in otherregions of ostial stenosis in visceral vessels such as the mesentericarteries and iliac arteries.

The present invention aims to provide a stent which overcomes theabovementioned problems of the prior art

Any discussion of documents, acts, materials, devices, articles or thelike which has been included in the present specification is solely forthe purpose of providing a context for the present invention. It is notto be taken as an admission that any or all of these matters form partof the prior art base or were common general knowledge in the fieldrelevant to the present invention as it existed before the priority dateof each claim of this application.

SUMMARY OF THE INVENTION

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps.

The present invention consists in an intraluminal stent comprising atubular body extending from a proximal end to a distal end, said tubularbody being capable of expanding or being expanded from a radiallycompressed state to a radially expanded state wherein, when at least inthe radially expanded state, the tubular body includes at least a firstflange member positioned at or adjacent to the proximal end of thetubular body and extending outwardly from said tubular body.

In one embodiment, the first flange member extends outwardly and awayfrom the proximal end of the tubular body of the stent to give thetubular body a trumpet-like appearance.

The first flange member may be integral with the proximal end of thetubular body and may extend to an outer rim. The outer rim may form alipped portion which may curve back in a general direction towards thedistal end of the tubular body. Alternatively, the first flange membermay be formed as a separate member to the remainder of the tubular bodywherein the first flange member is subsequently connected to the tubularbody

Preferably, the lipped portion is integral with the first flange membersuch that it forms a continuous curved structure extending initiallyoutwardly and away from the proximal end of the tubular body beforecurving back in a general direction towards the distal end of thetubular body.

The first flange member is typically made from the same material as theremainder of the tubular body. Alternatively, the first flange membermay be made from a different material from the material of the remainderof the stent.

In another embodiment, the intraluminal stent includes a second flangemember positioned at or adjacent the distal end of the tubular body.

The second flange member preferably extends outwardly and away from thedistal end of the tubular body of the stent.

The second flange member may be integral with the distal end of thetubular body and may extend to an outer rim. The outer rim may form alipped portion which may curve back in a general direction towards theproximal end of the tubular body.

Preferably, the lipped portion is integral with the second flange membersuch that it forms a continuous curved structure extending initiallyoutwardly and away from the distal end of the tubular body beforecurving back in a general direction towards the proximal end of thetubular body.

The second flange member is typically made from the same material as theremainder of the tubular body. Alternatively, the second flange membermay be made from a different material than the material of the remainderof the stent. Additionally, the second flange member may be formed as aseparate member to the remainder of the tubular body and subsequentlyconnected to the tubular body.

Preferably, the first and second flange members are made during themanufacture of the intraluminal stent of the invention. The electedmethod for achieving such flanged members will primarily depend on thematerial selected to comprise the stent and the flange member althoughit is envisaged that both the tubular body of the stent and the flangemember would be formed by laser cutting/etching of a suitable materialsuch as stainless steel or Nitinol™. In this regard, the tubular body ofthe present invention may be made by providing a cylinder of thematerial to be used and laser cutting said material in the cylindricalform. The laser cutting typically results in the formation of a seriesof cells along the length of the circumference of the cylinder. Thecells may be of the same size along the length of the cylinder or mayvary in size along the length. This will be discussed in greater detailbelow.

In the embodiment wherein the tubular body is made from a shape memorymaterial such as Nitinol™, the cylinder of material is laser cut to formthe series of cells. The cylinder is then taken to the desiredtemperature to allow the material to achieve a “memory” of a certainexpanded configuration. At this temperature, a template is used to pushthe area of the cylinder which is to become the at least first flangemember outwardly relative to the remainder of the cylindrical tubularbody. The material of the cylinder is then cooled from this temperaturesuch that the material resumes a compressed substantially cylindricalshape without the flanged end. When the final stent made from thiscylinder is inserted into a vessel of a patient, it is preferable thatwhen the material is exposed to the body temperature of the patient ittakes on its “memorised” shape, that is, a tubular body having at leasta first flange member positioned at or adjacent to a proximal end of thetubular body.

In an embodiment wherein the material of the stent Is not a shape memorymaterial, it is envisaged that a pre-formed tubular body having at leasta first flange member positioned at least adjacent the proximal end ofthe tubular body is formed. The pre-formed tubular body may then belaser cut into a desired series of cells.

In a preferred embodiment, the cells of the tubular body may be ofvarying size and configuration along the length of the tubular body. Forexample, it is envisaged that the at least first flange member is madefrom a series of cells which are larger and/or more elongate than theremainder of the cells of the tubular body. Furthermore, it is preferredthat the cells of the flange member in addition to being more elongate,are formed at an angle to the remainder of the cells of the tubularbody.

The tubular body may further include a transition region adjacent the atleast first flange member. The transition region is preferably made upof a series of cells which have a small pore size relative to the cellsof the at least first flange member and the remainder of the tubularbody. In this embodiment, the transition region provides an area ofrelatively high expansile strength. In cases where the stent is used inostial stenosis, which will be discussed further below, the transitionregion has the advantage of “pinning back” an area of stenosis aroundthe ostium of a vessel.

The at least first flange member may comprise two cells located onopposing walls of the tubular body. In this embodiment the two cellsform strut members which have the effect of anchoring the stent in avessel, particularly when the stent is used to treat ostial stenosis asfurther discussed below. It should be noted, however, that the presentinvention encompasses all possible cell patterns in the wall of thetubular body and including the at least first flange member.

While the tubular body of the stent may be formed of a thinbiocompatible material such as Nitinol™ or stainless steel, other alloyssuch as tantalum or Elgiloy are also envisaged. The tubular body may bebare or may be coated with a material having an elastic property suchthat the coating material is capable of covering the tubular body inboth the radially compressed state and the radially expanded state.

In a preferred embodiment of the invention, the tubular body may beformed from other suitable biocompatible materials, selected, for bestresults, on the basis of the material's capacity to withstand thecompressive forces of the stenotic lesion and maintain patency of thevessel throughout the life of the stent.

Preferably, the intraluminal stent of the present invention is used inthe treatment of ostial stenosis although it is equally envisaged thatit could be used in any other form of stenosis. In ostial stenosis, theplaque or stenotic region is formed at the junction between apre-branching vessel and a post-branching vessel. The stenotic plaquesurrounds the ostium of the post-branching vessel which has the effectof narrowing the ostium of the post-branching vessel.

While the stent of the present invention may be used to treat ostialstenosis of the visceral arteries such as the renal and mesentericarteries, the iliac artery, and the sub-clavian artery, it may also beused to treat stenotic lesions in the peripheral vasculature and thecoronary circulation. However, the application of the invention for usein the treatment of stenotic disease is not to be understood as limitedto the vascular system only. The stent may be used to treat stenoticlesions in other vessels including, for example, those comprising thehepato-biliary and genito-urinary tracts

In the treatment of ostial stenosis, the first flange member ispreferably positioned within the pre-branching vessel. In thisembodiment, the first flange member typically engages at least a portionof the wall of the pre-branching vessel which surrounds the ostium ofthe post-branching vessel. The remainder of the tubular body of thestent can extend into the post-branching vessel. Accordingly, the atleast first flange member has the effect of anchoring the stent withinthe post-branching vessel thereby preventing longitudinal movement ofthe stent into the post-branching vessel. If such movement occurs, thestent moves away from the stenotic lesion and thereby does not have thedesired function of bridging the stenotic lesion.

In the embodiment of the invention which includes a second flange memberpositioned adjacent the distal end of the tubular body, when the stentis used in the treatment of ostial stenosis, the second flange member ispositioned within the post-branching vessel and preferably engages thewall of said post-branching vessel. This further secures theintraluminal stent within the post-branching vessel thereby preventinglongitudinal movement of the stent in the vessel.

The tubular body of the stent may further include at least oneengagement member. The at least one engagement member may be connectedto or integral with a wall of the tubular body at a position locatedintermediate the proximal end and the distal end of the tubular body.

Preferably, the tubular body includes more than one engagement memberwhich may comprise a number of spurs or other such members which extendoutwardly from the tubular body of the stent. When the stent is in use,the spurs extend towards and engage with the wall of the vessel in whichthe stent is positioned. This has the function of further securing thestent within the vessel.

In a further embodiment, rather than a spur, the at least one engagementmember may comprise a ridge or like area or a series of ridges ofincreased cross sectional diameter than those portions of the tubularbody immediately proximal and distal each ridge. When the stent is inuse, the ridge or like area or series of ridges extend(s) towards andengage(s) with the vessel wall thereby assisting in the securing of thestent in the vessel wall.

The at least one engagement member may be made from the same material asthe remainder of the tubular body or may be made from a differentmaterial. It is envisaged that the at least one engagement member may bemade from a shape memory material such as Nitinol™.

The connection between the at least one engagement member and thetubular body of the stent may be such that allows the at least oneengagement member to occupy a first angular relationship with anadjacent part of the tubular body when the tubular body is in itscompressed state wherein the at least one engagement member occupies asecond and different angular relationship with the tubular body when thetubular body is in its expanded state.

The at least one engagement member is preferably created during themanufacture of the stent of the invention. Where the tubular body andthe at least one engagement member are made from a shape memory materialsuch as Nitinol™, a cylinder of Nitinol™ is taken to a desiredtemperature to allow the material to achieve a “memory” of a certainconfiguration. If the at least one engagement member is a ridge asdescribed above, when the cylinder is taken to this temperature, atemplate is used to push the area of the cylinder which is to become theat least one engagement member outwardly from the remainder of thecylindrical tubular body. The material of the cylinder is then cooledfrom this temperature such that the material resumes its compressed andsubstantially cylindrical shape without the ridge. When the final stentmade from this cylinder is inserted into a vessel of a patient, it ispreferable that when the material is exposed to the body temperature ofthe patient it takes on its “memorised” shape, that is, a tubular bodyhaving at least one engagement member extending outwardly therefrom.

Alternatively, wherein the tubular body is made up of a series of cells,the at least one engagement member may comprise a number of cells linkedto one another wherein said cells extend around the circumference of thetubular body. Each cell preferably has an area of weakness which uponexpansion of the tubular body from the compressed state to the expandedstate buckles thereby forming a rib or a series of ribs for engagementwith the vessel. This embodiment may be useful wherein the tubular bodyis made from a material such as stainless steel.

In a further embodiment, the at least one engagement member may be madeup of a series of connector members which connect the cells on eitherside of the at least one engagement member. In this regard, theconnector members may be relatively straight members and may connectevery second cell on either side of the at least one engagement member.In this embodiment, when the tubular body moves from the radiallycompressed state to the radially expanded state, the free ends of everysecond cell which are not connected by the connector members turnoutwardly away from the tubular body and engage with the vessel wall.

The tubular body may be coated with materials to promote adhesion ofcells or cell growth to assist in securing the device tubular body inplace in the post-branching vessel It is further envisaged that thetubular body may be coated with any of a number of pharmaceuticalagents.

In a preferred embodiment, during use of the intraluminal stent of thepresent invention, the tubular body is initially in the radiallycompressed state to enable delivery of the stent through an introducercatheter. Upon deployment of the stent into a selected vessel, thetubular body may be caused to expand, or may be allowed to self-expandinto the expanded state.

There are at least three preferred mechanisms whereby the tubular bodymay change from the radially compressed state to the radially expandedstate. For instance, the tubular body may be expanded by the force of aninflating balloon within the tubular body or by some other mechanicallyapplied force.

Alternatively, the tubular body may be made from a shape memory materialas mentioned above wherein the patient's body temperature causes thetemperature of the tubular body to move towards the same temperature,thereby enabling the tubular body to self-expand and take on its“memorised” shape.

In a further embodiment, the tubular body may self expand followingdeployment of the tubular body from an introducer catheter used tointroduce the stent invention into the body of a patient. Thisparticular embodiment relies upon spring expansion of the material ofthe tubular body following release of the compressive force of theintroducer catheter.

The first and/or the second flange member may expand by a differentmechanism to the mechanism of expansion of the remainder of the tubularbody. For example the flange member(s) may be made from a shape memorymaterial such as Nitinol™ whereas the remainder of the tubular body maybe made from a spring expandable material such as stainless steel. Inthis case, upon deployment of the stent within a vessel, the flangemembers would take on their “memorised” shape and the remainder of thebody would spring into shape having been compressed in the deliverycatheter. Various combination of the above mechanisms are envisaged.

In a second aspect, the invention relates to a method of positioning anintraluminal stent according to the first aspect of the invention in avessel of a patient, the method comprising the steps of:

(i) introducing a catheter or other delivery device into a vein, arteryor other vessel in the body of a patient when the tubular body of theintraluminal stent is in the radially compressed state;

(ii) causing the intraluminal stent to be carried through the catheteror other delivery device to a target. site of stenosis at a bifurcationbetween a first pre-branching vessel and a second post-branching vessel;

(iii) causing or allowing the tubular body of the intraluminal stent toexpand such that the at least first flange member is positioned at leastpartially within the pre-branching vessel and the remainder of thetubular body of the stent extends into the post-branching vessel; and

(iv) withdrawing the catheter or other delivery device along with anyother apparatus used to introduce the intraluminal device into thevessel from the body of the patient.

The length and radially expanded diameter of the tubular body may bedetermined by the individual circumstances of the application to whichthe intraluminal device is to be put. Typically, the bifurcating vesselis assessed by X-ray or other similar examination and a suitablydimensioned device selected for that application.

The Intraluminal stent may have radio-opaque markers incorporated intothe tubular body to enable a surgeon to view the position of the stentwithin the vessels.

In a third aspect, the present invention provides a delivery system forthe delivery of the intraluminal stent of the first aspect to a targetvessel, said delivery system comprising an introducer catheter having anelongate tubular body to allow the passage therethrough of a placementcatheter, said placement catheter having an elongate body which extendsfrom a proximal end to a distal end and which carries the stent of thefirst aspect of the invention at a position intermediate said proximalend and said distal end, the delivery system further comprising amembrane which engages a portion of the tubular body of the intraluminalstent not comprising the at least first flange member and wherein saidmembrane acts to maintain said portion of the tubular body in itsradially compressed state.

In a fourth aspect, the present invention provides a method ofdelivering the intraluminal stent of the first aspect using the deliverysystem of the third aspect, said method comprising the steps of:

(i) introducing the introducer catheter into a vein, artery or othervessel in the body of a patient wherein the tubular body of theintraluminal stent is in the radially compressed state;

(ii) causing the intraluminal stent, the placement catheter and themembrane to be carried through the introducer catheter to a target siteof stenosis at a bifurcation between a first pre-branching vessel and asecond post-branching vessel;

(iii) introducing the distal end of the placement catheter into thepost-branching vessel from the pre-branching vessel until substantiallyonly the at least first flange member is still positioned within thepre-branching vessel;

(iv) withdrawing the introducer catheter to expose the at least firstflange member of the intraluminal stent;

(v) causing or allowing the at least first flange member to move fromits radially compressed state to its radially expanded state such thatit is caused to abut with at least a portion of the wall of thepre-branching vessel which surrounds the opening of the post-branchingvessel;

(vi) advancing the placement catheter and the membrane further into thepost-ranching vessel such that the compression on the portion of thetubular body substantially surrounded by the membrane, by said membraneis released, allowing said portion of the tubular body to move from itsradially compressed state to its radially expanded state and intoabutment with at least a portion of the wall of the post-branchingvessel; and

(vii) withdrawing the placement catheter together with the membranethrough the expanded tubular body.

In a fifth aspect the present invention provides a delivery system forthe delivery of an intraluminal stent to a target vessel, said deliverysystem comprising an introducer catheter having an elongate tubular bodyto allow the passage therethrough of a placement catheter, saidplacement catheter having an elongate body which extends from a proximalend to a distal end and which carries the intraluminal stent at aposition intermediate said proximal end and said distal end; thedelivery system further including a membrane which engages at least aportion of the intraluminal stent such that said portion of the stent isprevented from moving from a first radially compressed state to a secondradially expanded state.

In this fifth aspect the stent can have the features of the stentaccording to the first aspect of the invention defined herein.

Preferably, the intraluminal stent is made from a shape memory materialsuch as Nitinol™. In this embodiment, where the first flange member ispresent and when the introducer catheter is withdrawn to expose the atleast first flange member of the intraluminal stent, said first flangemember is exposed to the body temperature of the patient whereupon itmoves to its “memorised” position, that is, flaring outwardly from theremainder of the tubular body of the stent. In the treatment of ostialstenosis, this forms the anchor for the stent as the flange memberengages with the wall of the pre-branching vessel around the ostium ofthe post-ranching vessel.

To ensure that the stent is appropriately positioned before theintroducer catheter is withdrawn, the at least first flange member mayhave radio-opaque markers incorporated in its structure. Accordingly, inthis embodiment, the surgeon would be able to determine the exactpositioning of the at least first flange member within a vessel(s) ofthe patient. Not until the at least first flange member was positionedwithin the pre-branching vessel at an area adjacent the opening of thepost-branching vessel and the remainder of the tubular body extendinginto the post-branching vessel would the introducer catheter bewithdrawn.

As discussed above, the remainder of the tubular body of the stent whichis positioned within the post-branching vessel is typically engaged bythe membrane. In this regard, the membrane may extend around thecircumference of the tubular body.

The membrane is preferably made from a suitably strong material to actas a compressive force upon the tubular body thereby preventing thetubular body from moving into the radially expanded state.

The membrane may be made of a biodegradable material and could thereforebe left within the body of the patient although preferably, the membraneis also withdrawn with the placement catheter. Whichever arrangement ischosen, the effect is to release the pressure exerted on the tubularbody such that it can move to its radially expanded state.

In the case of use of the stent in the treatment of ostial stenosis, themembrane preferably engages with all of the tubular body of the stentapart from the at least first flange member. Accordingly, when theintroducer catheter is withdrawn, the at least first flange member isfree to move from its radially compressed state to its radially expandedstate. In this embodiment, it is envisaged that the membrane around theat least one portion of the tubular body may be broken to enable the atleast one portion of the tubular body to move from its radiallycompressed state to its radially expanded state.

In one embodiment, the placement catheter may include a balloon memberpositioned at least partially internal the tubular body of theintraluminal stent. Upon inflation of the balloon member, theintraluminal stent is forced radially outwardly which has the effect ofbreaking the membrane. With the membrane broken, the at least oneportion of the tubular body is free to move into its radially expandedstate. It is further envisaged that the membrane may include a frangibleregion which breaks upon the exertion of pressure caused by theinflation of the balloon member.

It is also further envisaged that the membrane may not break but ratherthe membrane is caused to radially expand with the radial expansion ofthe tubular body of the intraluminal stent. Such radial expansion mayresult from the force exerted by the inflation of the balloon member.

As discussed above, the membrane may be biodegradable in which case,upon placement of the tubular body in a target vessel, the membrane maydegrade thereby allowing the tubular body to move to its radiallyexpanded state.

The membrane can deliver any of a number of pharmaceutical agents to atarget vessel. In this embodiment, the membrane may be coated with suchagents. Furthermore, the membrane may comprise a number of layerscarrying different pharmaceutical agents. Each layer may bebiodegradable to expose another layer.

In a sixth aspect, the present invention provides a delivery system forthe delivery of an intraluminal stent to a target vessel, saidintraluminal stent being movable from a first radially compressed stateto a second radially expanded state at a target site within the vessel,said delivery system comprising a catheter which in turn comprises anelongate body which extends from a proximal end to a distal end whereinthe elongate body extends through an internal lumen of the intraluminalstent such that said intraluminal stent substantially surrounds aportion of the catheter; the delivery system further comprising at leastone compression member which holds the intraluminal stent in its firstradially compressed state and a release member which causes release ofthe compression member and allows the intraluminal stent to move to itssecond radially expanded state.

It is preferred that the delivery system is used to deliver a selfexpanding intraluminal stent to a target site.

In one embodiment, the compression member of the sixth aspect forms amembrane around the intraluminal stent. In this regard, the membrane ismade from a suitably strong yet flexible material to compress theintraluminal stent and prevent said stent moving from its first radiallycompressed state to its second radially expanded state.

In a further embodiment, it is envisaged that the compression memberincludes a tie member or a series of tie members which hold theintraluminal stent around the catheter and prevent the intraluminalstent moving from its first compressed state to its second expandedstate. For example, the tie member(s) may be sutures which have apre-determined breaking strength. The sutures may be bonded to theintraluminal stent such that they do not form free particles during andafter the deployment of said stent.

Alternatively, the compression member may comprise one or more of acollar, ring or spiral wrap or combinations thereof around theintraluminal stent.

The advantage of the delivery system of the sixth aspect is that theself expanding intraluminal stent may be delivered to a target sitewithout the requirement of a bulky introducer catheter to hold theintraluminal stent in its first radially compressed state. In thisregard, the compression member of the delivery system holds theintraluminal stent in its radially compressed state until the stent isadvanced on the catheter to the target site.

When the intraluminal stent reaches the target site, the release membermay be activated to release the compressive force of the compressionmember on the intraluminal stent. In this regard, the release member maycomprise a balloon member positioned along the length of the elongatebody of the catheter. The balloon member may form the portion of theelongate body of the catheter which is substantially surrounded by theintraluminal stent. The balloon member may move from a deflated stateduring delivery of the catheter to a target site, to an inflated stateat said target site. Movement of the balloon member to the inflatedstate may release the compressive force of the compression member.

Particularly, where the compression member is a membrane which surroundsthe intraluminal stent, it is preferred that said membrane includes atleast one frangible region such that when the balloon member moves fromits deflated to inflated state, the frangible region(s) is broken andthe intraluminal stent allowed to move to its second radially expandedstate. In this regard, in a preferred embodiment wherein theintraluminal stent is a self expanding stent, breaking the compressionmember at the frangible region(s) allows said stent to spring to itssecond radially expanded state, that is, the balloon member is typicallyinflated only a sufficient degree to break the engagement betweencompression member and stent and need not be inflated further to causethe intraluminal stent to move from its first radially compressed stateto its second radially expanded state. In one embodiment, said frangibleregion may comprise one or more perforations, such as a line ofperforations, in the body of the membrane.

In the embodiment wherein the compression member comprises a number ofsutures, as mentioned above, the sutures holding the intraluminal stentto the catheter have a predetermined breaking strength. Accordingly,when the balloon member moves from its deflated state to its inflatedstate, the sutures break thereby allowing the intraluminal stent to moveto its second radially expanded state.

Similarly, in further embodiments, the movement of the balloon memberfrom its deflated to its inflated state may cause said one or more ofthe collar, ring or spiral wrap to release their compressive force.

In another embodiment, where the compression member forms a membranearound the intraluminal stent, it is envisaged that said membrane has aperforation along at least a portion of its length. The release memberin this embodiment may be a pull suture which is aligned with and/orthreaded through the perforation of the membrane. The pull suturetypically extends to a location outside the body or is connected to anactuator member located outside the body such that when the intraluminalstent is in position at a target site, the pull suture is drawn in adirection towards the proximal end of the intraluminal stent such thatthe perforation is broken and the compressive force of the membranereleased from the intraluminal stent which may then move to its radiallyexpanded state.

In a further embodiment of this aspect, the compression member is anexpandable membrane, The membrane can be sealed around the stent. Inthis aspect, the release member comprises a fluid that can be deliveredto the sealed membrane and so expand the membrane.

In one embodiment, the fluid can be delivered into the sealed membraneby the catheter through apertures therein.

In a preferred embodiment, the membrane breaks into one or more portionson undergoing a predetermined degree of expansion. Said one or moreportions of the membrane can be connected to the catheter and arewithdrawable from the target vessel on withdrawal of the cathetertherefrom.

In a further embodiment, the membrane can contain or include one or morepharmaceutical agents. In another embodiment, one or more pharmaceuticalagents can be delivered with the fluid from the catheter arid into thepocket formed by the sealed membrane.

In a further embodiment, the stent can be a self-expanding stent thatexpands on expansion of the membrane. In another embodiment, the stentis a passive stent that requires expansion by a secondary mechanism,such as a balloon catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a cut-away view of anatomical structures of the abdomen of asubject.

FIG. 1 b is a magnified view of part of the structure depicted in FIG. 1a.

FIG. 2 Is a perspective view of one embodiment of the intraluminal stentof the invention.

FIG. 3 a is a view of the cell structure of the intraluminal stentdepicted in FIG. 2 when the stent is in an expanded state.

FIG. 3 b is a view of the cell structure of the intraluminal stentdepicted in FIG. 2 when the stent is in a compressed state.

FIG. 4 is a perspective view of another embodiment of the intraluminalstent of the invention.

FIG. 5 a is a view of the cell structure of the intraluminal stentdepicted in FIG. 4 when the stent is in an expanded state.

FIG. 5 b is a view of the cell structure of the intraluminal stentdepicted in FIG. 4 when the stent is in a compressed state.

FIG. 6 is a perspective view of a further embodiment of the intraluminalstent of the invention.

FIG. 7 a is a view of the cell structure of the intraluminal stentdepicted in FIG. 6 when the stent is in an expanded state.

FIG. 7 b is a view of the cell structure of the intraluminal stentdepicted in FIG. 6 when the stent is in a compressed state.

FIG. 8 is a side elevational schematic view of an embodiment of theinvention.

FIG. 9 is a side elevational schematic view of a further embodiment ofthe present invention.

FIG. 10 is a cross-sectional view of a further embodiment of the presentinvention.

FIG. 11 is a schematic view of a delivery catheter according to thepresent Invention.

FIGS. 12 a to 12 d depict placement of the intraluminal stent accordingto the present invention in a vessel using the delivery catheter shownin FIG. 11.

FIGS. 13 a, 13 b and 13 c are cross-sectional views of furtherembodiments of the delivery catheter shown in FIG. 11.

FIGS. 14 a, 14 b and 14 c are views of further embodiments of thepresent invention.

FIG. 14 d shows the cells structure of the embodiment of the inventiondepicted in FIG. 14 b.

FIGS. 15 a and 15 b show schematic views of a delivery system of furtheraspect of the invention.

FIG. 15 c is a cross-sectional view showing the intraluminal stent andcompression member of the delivery system depicted in FIG. 15 b.

FIG. 16 is a schematic view of a further embodiment of the deliverysystem of the invention.

FIGS. 17 a and 17 b are schematic views of a further embodiment of adelivery system according to the present invention.

FIGS. 18 a and 18 b are schematic views of a still further embodiment ofa delivery system according to the present invention.

PREFERRED MODE OF CARRYING OUT THE INVENTION

The intraluminal stent of the present invention is generally depicted as10 in the accompanying drawings.

Preferably, the intraluminal stent of the present invention is used inthe treatment of ostial stenosis although it is equally envisaged thatit could be used in the treatment of any other form of stenosis. Inostial stenosis, the plaque or stenotic region 9 is formed at thejunction between a pre-branching vessel 21 such as the aorta and apost-branching vessel 20 such as the renal artery which has the effectof narrowing the opening (ostium) of the post-branching vessel 20.

The intraluminal stent 10 comprises a tubular body 11 extending from aproximal end 12 to a distal end 13. The tubular body 11 is capable ofexpanding or being expanded from a radially compressed state (asdepicted In FIGS. 3 b, 5 b and 7 b) to a radially expanded state (asdepicted in FIGS. 3 a, 5 a and 7 a). When in the radially expandedstate, the tubular body 11 includes a first flange member 15 positionedadjacent the proximal end 12 of the tubular body 11, with the firstflange member 15 having a greater diameter than the diameter of theremainder of the tubular body 11.

The first flange member 15 extends outwardly and away from the proximalend 12 of the tubular body 11 giving the stent a trumpet-like shape asdepicted in FIG. 2.

The first flange member 15 is shown as forming a continuous, integralstructure with the tubular body 11 and is typically made from the samematerial as the remainder of the tubular body 11.

During use of the intraluminal stent 10 (in the present case, the term“use” refers to the treatment of ostial stenosis), the tubular body 11is initially in the radially compressed state to enable delivery of thestent 10 through an introducer catheter. Upon deployment of the stent 10into a selected vessel, the tubular body may be caused to expand, or maybe allowed to self-expand into the expanded state. The first flangemember 15 is positioned at least partially within pre-branching vessel21 and the remainder of the tubular body of the stent extends into thepost-branching vessel 20.

In use, the first flange member 15 is positioned in the pre-branchingvessel 21, such as, for example, the aorta. The first flange member 15typically engages at least a portion of the pre-branching vessel wallsurrounding the ostium of the post-branching vessel 20 with theremainder of the tubular body 11 extending Into the post-branchingvessel 20. Accordingly, the first flange member 15 has the effect ofanchoring the stent 10 within the post-branching vessel 20 therebypreventing longitudinal movement of the stent into the post-branchingvessel 20.

While the tubular body 11 of the stent may be formed of a thinbiocompatible material such as Nitinol™ or stainless steel, other alloyssuch as tantalum or Elgiloy may be used. In the examples depicted, thestent is made from Nitinol™.

As depicted in FIGS. 3 a, 3 b, 5 a, 5 b and 7 a, 7 b, a cylinder ofNitinol™ is laser cut to form a series of cells 22. The cylinder is thentaken to the desired temperature to allow the material to achieve a“memory” of a certain configuration. At this temperature, a template isused to push the area of the cylinder 23 which is to become the firstflange member 15 outwardly from the remainder of the cylinder. Thematerial of the cylinder is then cooled from this temperature such thatthe material resumes its cylindrical shape without the flange member.When the final stent 10 made from this cylinder is inserted into avessel of a patient, the material takes on its “memorised” shape, thatis, a tubular body having a first flange member positioned at leastadjacent the proximal end 12 of the tubular body 11.

In an embodiment wherein the material of the stent is not a shape memorymaterial, it is envisaged that a pre-formed tubular body having at leasta first flange member positioned at least adjacent the proximal end ofthe tubular body is formed. The pre-formed tubular body may then belaser cut into a desired series of cells.

As depicted in the figures, the cells 22 of the tubular body 11 may beof varying size or configurations along the length of the tubular body11. In each of the figures, the first flange member 15 is made up of aseries of elongate cells 23 which are angled from the remainder of thecells of the tubular body. This region is generally depicted as (1) inthe drawings. The region adjacent the first flange member 15 is depictedas (2). As can be seen, the cells of this region are generally of alarge “bat-wing” shape which confer the desired flexibility while at thesame time a certain degree of rigidity to the stent 10. In FIG. 3 a,region (2) extends from a region adjacent the first flange member 15along the remainder of the length of the tubular body 11. In FIG. 5 a,region (2) is interrupted by region (x) which comprises a ring of cells25 around the tubular body 11, wherein each cell is formed from astraight link 26 with a central hole 27. In one embodiment, wherein thematerial of the stent is not a necessarily a shape memory material, whenthe stent 10 is moved from a compressed state to an expanded state, thecells on either side of region (x) are forced closer together therebycausing the straight links 26 to buckle outwardly of the tubular body 11at a fold adjacent the central hole 27. This creates a ridge 31 on thetubular body 11 which is depicted in FIG. 4 and will be discussed infurther detail below.

Where the tubular body 11 is made from a shape memory material such asNitinol™, a cylinder of Nitinol™ is taken to a desired temperature toallow the material to achieve a “memory” of a certain configuration. Ifa ridge 31 as depicted in FIG. 4 is to be formed, when the cylinder istaken to this temperature, a template is used to push the area of thecylinder which is to become the ridge 31 outwardly from the remainder ofthe cylindrical tubular body. The material of the cylinder is thencooled from this temperature such that the material resumes itscylindrical shape without the ridge 31. When the final stent 10 madefrom this cylinder is inserted into a vessel of a patient, it ispreferable that when the material is exposed to the body temperature ofthe patient it takes on its “memorised” shape, that is, a tubular body11 having a ridge 31 as depicted in FIG. 4.

In a further embodiment of the invention as depicted in FIGS. 6, 7 a and7 b, the stent 10 has a first flange member 15 and a second flangemember 28. In this embodiment, the cells 23 of the first flange member15 are of an elongate shape and make up region (1). Region (2) of thisembodiment comprises a series of “bat-wing” cells 22 which extend intofrom region (1) to region (3). Region (3) comprises the second flangemember 28 and is made of a series of relatively large diagonal-shapedcells. Where the tubular body 11 is made from a shape memory materialsuch as Nitinol™, the second flange member 28 may be formed In the samemanner as described above for the first flange member 15.

In another embodiment of the invention as depicted in FIG. 8, thetubular body is made up of regions (1), (2) and (3) wherein region (1)comprises the first flange member 15, Region (2) is made up of a seriesof cells 22 having a smaller, tighter pore size than the cells 22 ofregions (1) and (3). This provides a region of relatively high expansilestrength which acts to exert a force on a surrounding stenotic regionwhen the stent is in use.

In one embodiment as depicted In FIG. 9, the first flange member 15comprises two cells 22 located on opposing walls of the proximal end 12of the tubular body 11. In this embodiment, the two cells 22 form strutsto engage the area surrounding the ostium of a post-branching vessel 20.

In a particularly preferred embodiment of the invention as depicted inFIG. 10, the first flange member 15 in addition to extending outwardlyand away from the proximal end 12 of the tubular body 11, doubles backon itself in a direction generally towards the distal end 13 of thetubular body 11. The first flange member 15 in this embodiment thereforeforms a lipped structure which provides a good anchorage of the stent 10when it is in use. Particularly, the lipped portion engages a region ofthe pre-branching vessel 21 around the ostium of the post branchingvessel 20 thereby preventing movement of the stent 10 into thepost-branching vessel 20 such that the stent does not bridge an area ofstenosis around the ostium of the post-branching vessel.

As depicted in FIG. 4, the tubular body 11 also includes an engagementmember 30. The engagement member 30 is connected to or integral with awall of the tubular body 11 at a position located intermediate theproximal end 12 and the distal end 13 of the tubular body 11.

The engagement member 30 depicted in FIG. 4 is ridge 31. When the stent10 is in use, the ridge 31 extends towards and engages with thepost-branching vessel 20 wall thereby securing the stent in thepost-branching vessel 20.

In a further embodiment depicted in FIGS. 14 a-14 d, the engagementmember 30 may be made up of a series of connector members 51 whichconnect the cells on either side of the at least one engagement member30. In this regard, the connector members 51 may be relatively straightmembers and may connect every second cell on either side of the at leastone engagement member. In this embodiment, when the tubular body movesfrom the radially compressed state to the radially expanded state, thefree ends 51 of every second cell which are not connected by theconnector members 50 turn outwardly away from the tubular body and areengageable with the vessel wall.

As mentioned above, the stent 10 of the present invention is used in thetreatment of ostial stenosis including ostial stenosis of the visceralarteries such as the renal and mesenteric arteries, the iliac artery andthe sub-clavian artery. Further, in addition to the treatment ofstenotic lesions in the peripheral vasculature, the stent 10 may be usedin the treatment of vessels comprising the coronary circulation.

FIG. 11 shows a delivery catheter 40 for the delivery of theintraluminal stent 10. The delivery catheter 40 includes an introducercatheter 41 having an elongate tubular body to allow the passagetherethrough of a placement catheter 42. The placement catheter 42 hasan elongate body extending from a proximal end 43 to a distal end 44,the placement catheter carrying the stent 10 having body 11 at aposition intermediate its proximal end 43 and its distal end 44. Thedelivery catheter 40 further includes a membrane 45 positioned aroundthe placement catheter 42 and connected to distal end 44 wherein themembrane 45 is positioned such that it does not surround the firstflange member 15 of the intraluminal stent 10 and wherein the membrane45 acts to compress the remainder of the tubular body and prevent itfrom moving to the radially expanded state.

When the intraluminal stent 10 is to be used to bridge an ostialstenosis, it is introduced as follows:

Step 1: the introducer catheter 41 is introduced by way of a vein,artery or other vessel into the pre-branching vessel 21 of a patent. Itshould be noted that the tubular body of the intraluminal stent is inits radially compressed state;

Step 2: the distal end 44 of the placement catheter 42 is introducedinto the post-branching vessel 20 from the pre-branching vessel 21 untilsubstantially only the first flange member 15 is still positioned withinthe pre-branching vessel 21;

Step 3: the introducer catheter 41 is pulled back to expose the firstflange member 15 of the intraluminal stent 10;

Step 4: the first flange member 15 moves from its radially compressedstate to its radially expanded state such that it abuts with at least aportion of the wall of the pre-branching vessel 21 which surrounds theostium of the post-branching vessel 20. It should be noted that in theexample depicted, the stent is made from Nitinol™. Accordingly, in itsfirst radially compressed state, the first flange member 15 simply formspart of the cylinder (as shown in FIG. 11). Being exposed to thesurrounding body temperature, the flange member 15 takes on its“memorised” expanded state which is the outwardly flared structuredescribed above. The expansion of the first flange member 15 anchors thestent 10 such that the remainder of the tubular body 11 cannot move anyfurther downstream within the post-branching vessel 20;

Step 5: the placement catheter 42 and the membrane 45 are advanceddownstream into the post-branching vessel 20 such that the portion oftubular body previously compressed by the membrane 45 is caused orallowed to move from its radially compressed state to its radiallyexpanded state such that it is caused to abut with at least a portion ofthe wall of the post-branching vessel 20;

Step 6: withdrawing the placement catheter 42 together with the membrane45 through the expanded tubular body 11. In this regard, it is preferredthat the membrane 45 is spring connected to the placement catheter suchthat it is biased against the placement catheter 42. This has theadvantage that the membrane 45 is held against the placement catheter 42during withdrawal of the placement catheter 42 thereby preventingsnagging of the membrane on the radially expanded stent 10.

To ensure that the stent 10 is appropriately positioned before theintroducer catheter 41 is withdrawn, the first flange member 15 may haveradio-opaque markers Incorporated in its structure. Accordingly, thesurgeon, would be able to determine the exact positioning of the firstflange member 15 within the vessel of the patient. Not until the atleast first flange member 15 is positioned within the pre-branchingvessel 21 at an area adjacent the opening of the post-branching vessel20 would the introducer catheter 41 be withdrawn.

In a further embodiment of the invention as depicted in FIG. 13 a, thesystem has a membrane 47 which engages with at least a portion 48 of theintraluminal stent 10 and maintains said portion in its radiallycompressed state. As depicted, the membrane 47 engages with all of thetubular body 11 of the stent 10 apart from the first flange member 15.Accordingly, when the introducer catheter 41 is withdrawn, the firstflange member 15 is free to move from its radially compressed state toits radially expanded state.

In the embodiment depicted in FIGS. 13 b and 13 c, the placementcatheter 42 includes a balloon member 49 positioned at least partiallyinternal the tubular body 11 of the intraluminal stent 10. Uponinflation of the balloon member 49, the tubular body 11, is forcedradially outwardly which has the effect of breaking the membrane 47.With the membrane 47 broken, the at least one portion 48 of the tubularbody 11 is free to move into its radially expanded state.

The delivery system of a further aspect of the invention is generallydepicted as 100 in FIGS. 15-17. The delivery system 100 is used for thedelivery of an intraluminal stent 101 to a target vessel.

As depicted, the intraluminal stent 101 is movable from a first radiallycompressed state (see FIG. 15 a) to a second radially expanded state(see FIG. 15 b).

The delivery system 100 includes a catheter 102 comprising an elongatebody which extends from a proximal end 104 to a distal end 105. Theelongate body extends through an internal lumen of the intraluminalstent 101 such that the intraluminal stent 101 substantially surrounds aportion of the catheter 102.

The delivery system 100 further includes a compression member whichholds the intraluminal stent 101 in its first radially compressed stateand a release member 107 which causes release of the compression memberand allows the intraluminal stent to move to its second radiallyexpanded state.

The delivery system 100 is used to deliver a self-expanding intraluminalstent to a target site.

As shown in FIGS. 15 a-15 c, the compression member is a membrane 109around the intraluminal stent. In this regard, the membrane 109 is madefrom a suitably strong yet flexible material to compress theintraluminal stent and prevent the stent moving from its first radiallycompressed state to its second radially expanded state.

The release member 107 comprises a balloon member 108 positioned alongthe length of the elongate body of the catheter 102. The balloon member108 is substantially surrounded by the intraluminal stent 101 and whenthe balloon member 108 is inflated the intraluminal stent is forcedradially outward.

The membrane 109 includes a series of perforations along its. lengthwhich are broken upon inflation of the balloon member 108 (as shown inFIG. 15 c). FIG. 15 c depicts the expanded intraluminal stent 101 andthe separated portions of the membrane 109. As shown, the separatedportions of the membrane 109 remain attached to the stent 101 onexpansion of the stent. In another embodiment, the membrane 109 isattached at its proximal end to the catheter 102 such that it may bewithdrawn from the target vessel with the catheter 102.

The delivery system of FIG. 16 operates in a manner similar to thatdescribed above except that the compression member comprises a number oftie members or sutures 111 which hold the intraluminal stent 101 aroundthe catheter 102 and prevent the intraluminal stent 101 moving from itsfirst compressed state to its second expanded state.

In this embodiment, the sutures 111 holding the intraluminal stent 101to the catheter 102 have a predetermined breaking strength. Accordingly,when the balloon member 108 moves from its deflated state to itsinflated state, the sutures 111 break thereby allowing the intraluminalstent 101 to move to its second radially expanded state.

Another embodiment of a delivery system is depicted in FIGS. 17 a to 17b. In this embodiment the compression member comprises a membrane 109around the intraluminal stent 101. The membrane has a perforation alongat least a portion of its length. The release member in this embodimentis a pull suture 112 which is aligned with and/or threaded through theperforation of the membrane 109. The pull suture 112 typically extendsto a location outside the body or is connected to an actuator memberlocated outside the body such that when the intraluminal stent 101 is inposition at a target site, the pull suture 112 is drawn in a directiontowards the proximal end of the intraluminal stent 101 such that theperforation is broken and the compressive force of the membrane 109released from the intraluminal stent 101 which may then move to itsradially expanded state.

In the embodiment of the delivery system depicted in FIG. 18, thecompression member is an expandable membrane 121. The membrane 121 issealed around the stent 101 on delivery of the stent 101 into the targetvessel.

The release member comprises a fluid that can be delivered to the sealedmembrane 121 and so expand the membrane 121. The fluid is delivered intothe sealed membrane 121 by the catheter 102 through apertures 122therein.

The membrane 121 breaks into one or more portions 121 a and 121 b onundergoing a predetermined degree of expansion. In the depictedembodiment, the proximal end 123 of the portions are connected to thecatheter 102 and are withdrawable from the target vessel on withdrawalof the catheter 102 therefrom.

In this embodiment, the membrane 121 can contain or include one or morepharmaceutical agents. In another embodiment, one or more pharmaceuticalagents can be delivered with the fluid from the catheter 102 and intothe pocket formed by the sealed membrane 121.

In the depicted embodiment, the stent 101 is a self-expanding stent thatexpands in the direction depicted by arrows A on expansion of themembrane 121. It will be appreciated that in another embodiment, thestent can be a passive stent that requires expansion by a secondarymechanism, such as a balloon catheter.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

1-54. (canceled).
 55. An intraluminal stent comprising a tubular bodyextending from a proximal end to a distal end, said tubular body beingcapable of expanding or being expanded from a radially compressed stateto a radially expanded state wherein, when at least in the radiallyexpanded state, the tubular body comprises at least a first flangemember positioned at or adjacent to the proximal end of the tubular bodyand extending outwardly from said tubular body.
 56. The intraluminalstent of claim 55 wherein said first flange member comprises a main bodythat extends from one end that is connected to or integral with theproximal end of the tubular body to a free end of the flange member. 57.The intraluminal stent of claim 56 wherein the cross-sectional diameterof the flange member increases as it extends from said one end to saidfree end.
 58. The intraluminal stent of claim 56 wherein the main bodyof the flange member extends from the tubular body at substantiallyright angles to said tubular body.
 59. The intraluminal stent of claim56 wherein the main body of the flange member comprises a curved memberthat initially extends in a linear fashion away from the proximal end ofthe tubular body before curling back in a direction substantiallytowards the distal end of the tubular body.
 60. The intraluminal stentof claim 55 further comprising a second flange member positioned at oradjacent the distal end of the tubular body.
 61. The intraluminal stentof claim 60 wherein said second flange member comprises a main body thatextends from one end that is connected to or integral with the distalend of the tubular body to a free end of said second flange member. 62.The intraluminal stent of claim 55 when made from a shape memorymaterial including Nitinol™.
 63. The intraluminal stent of claim 55wherein the tubular body of the stent is made up of a series of cells.64. The intraluminal stent of claim 63 wherein the cells vary in sizeand configuration along the length of the tubular body.
 65. Theintraluminal stent of claim 64 wherein the first flange member is madefrom a series of cells which are larger and/or more elongate than theremainder of the cells of the tubular body.
 66. The intraluminal stentof claim 65 wherein the cells of the flange member are at an anglerelative to the remainder of the cells of the tubular body.
 67. Theintraluminal stent of claim 55 when used in the treatment of ostialstenosis including ostial stenosis of the renal and mesenteric arteries,the iliac artery, the sub-clavian artery and the coronary circulation.68. The intraluminal stent of claim 67 wherein the first flange memberis positionable within a pre-branching vessel of the ostial stenoticregion and wherein said first flange member substantially engages atleast a portion of the wall of the pre-branching vessel which surroundsthe ostium of a post-branching vessel.
 69. The intraluminal stent ofclaim 68 wherein the part of the tubular body of the stent notcomprising the first flange member is extendable into the post-branchingvessel and wherein the first flange member anchors said part of thetubular body within the post-branching vessel thereby preventinglongitudinal movement of the intraluminal stent into the post-branchingvessel.
 70. The intraluminal stent of claim 55 wherein the tubular bodyof the stent further includes at least one engagement member which isconnected to or integral with a wall of the tubular body at a positionlocated intermediate the proximal end and the distal end of the tubularbody.
 71. The intraluminal stent of claim 55 wherein the tubular body iscoated with materials to promote adhesion of cells or cell growth. 72.An intraluminal stent comprising a tubular body and a flange memberconnected to or integral with said tubular body, wherein the tubularbody and the flange member are moveable between a radially compressedstate and a radially expanded state and wherein further, when in theirradially compressed states, the tubular body and the flange membercomprise a stent having a substantially uniform cross-sectional diameterand when in their radially expanded states, at least a portion of theflange member has a greater cross-sectional diameter than thecross-sectional diameter of the tubular body.
 73. A method ofpositioning the intraluminal stent of claim 55 in a vessel of a patient,the method comprising the steps of: (i) introducing a catheter or otherdelivery device into a vein, artery or other vessel in the body of apatient when the tubular body of the intraluminal stent is in theradially compressed state; (ii) causing the intraluminal stent to becarried through the catheter or other delivery device to a target siteof stenosis at a bifurcation between a first pre-branching vessel and asecond post-branching vessel; (iii) causing or allowing the tubular bodyof the intraluminal stent to expand such that the at least first flangemember is positioned at least partially within the pre-branching vesseland the remainder of the tubular body of the stent extends into thepost-branching vessel; and (iv) withdrawing the catheter or otherdelivery device along with any other apparatus used to introduce theintraluminal device into the vessel from the body of the patient.
 74. Adelivery system for the delivery of the intraluminal stent of claim 55to a target vessel, said delivery system comprising an introducercatheter having an elongate tubular body to allow the passagetherethrough of a placement catheter, said placement catheter having anelongate body which extends from a proximal end to a distal end andwhich carries the stent of claim 1 at a position intermediate saidproximal end and said distal end, the delivery system further comprisinga membrane which engages a portion of the tubular body of theintraluminal stent not comprising the at least first flange memberwherein said membrane maintains said portion of the tubular body in itsradially compressed state.
 75. A method of delivering the intraluminalstent of claim 55 using the delivery system of claim 20, said methodcomprising the steps of: (i) introducing the introducer catheter into avein, artery or other vessel in the body of a patient wherein thetubular body of the intraluminal stent is in the radially compressedstate; (ii) causing the intraluminal stent, the placement catheter andthe membrane to be carried through the introducer catheter to a targetsite of stenosis at a bifurcation between a first pre-branching vesseland a second post-branching vessel; (iii) introducing the distal end ofthe placement catheter into the post-branching vessel from thepre-branching vessel until substantially only the at least first flangemember is still positioned within the pre-branching vessel; (iv)withdrawing the introducer catheter to expose the at least first flangemember of the intraluminal stent; (v) causing or allowing the at leastfirst flange member to move from its radially compressed state to itsradially expanded state such that it is caused to abut with at least aportion of the wall of the pre-branching vessel which surrounds theopening of the post-branching vessel; (vi) advancing the placementcatheter and the membrane further into the post-branching vessel suchthat the compression on the portion of the tubular body substantiallysurrounded by the membrane, by said membrane is released, allowing saidportion of the tubular body to move from its radially compressed stateto its radially expanded state and into abutment with at least a portionof the wall of the post-branching vessel; and (vii) withdrawing theplacement catheter with or without the membrane through the expandedtubular body.
 76. A delivery system for the delivery of an intraluminalstent to a target vessel, said delivery system comprising an introducercatheter having an elongate tubular body to allow the passagetherethrough of a placement catheter, said placement catheter having anelongate body which extends from a proximal end to a distal end andwhich carries the intraluminal stent at a position intermediate saidproximal end and said distal end; the delivery system further comprisinga membrane which engages at least a portion of the intraluminal stentsuch that said portion of the stent is prevented from moving from afirst radially compressed state to a second radially expanded state. 77.The delivery system of claim 74 wherein the membrane extends around thecircumference of the tubular body of the intraluminal stent.
 78. Thedelivery system of claim 77 wherein the membrane is made from a suitablystrong material to act as a compressive force upon the stent therebypreventing the stent from moving to its radially expanded state.
 79. Thedelivery system of claim 74 wherein the placement catheter includes aballoon member which is positioned at least partially within an internallumen of the tubular body of the intraluminal stent.
 80. The deliverysystem of claim 79 wherein inflation of the balloon member forces theintraluminal stent radially outwardly thereby breaking a region of themembrane.
 81. The delivery system of claim 74 wherein the membranecontains or includes a pharmaceutical agent.
 82. The delivery system ofclaim 81 wherein said membrane comprises a reservoir member to hold thepharmaceutical agent within the membrane.
 83. A delivery system for thedelivery of an intraluminal stent to a target vessel, said intraluminalstent being movable from a first radially compressed state to a secondradially expanded state at a target site within the vessel, saiddelivery system comprising a catheter which in turn comprises anelongate body which extends from a proximal end to a distal end whereinthe elongate body extends through an internal lumen of the intraluminalstent such that said intraluminal stent substantially surrounds aportion of the catheter; the delivery system further comprising at leastone compression member which holds the intraluminal stent in its firstradially compressed state and a release member which causes release ofthe compression member and allows the intraluminal stent to move to itssecond radially expanded state.
 84. The delivery system of claim 83 whenused to deliver a self expanding intraluminal stent to a target site.85. The delivery system of claim 83 wherein the compression membercomprises a membrane around the intraluminal stent.
 86. The deliverysystem of claim 83 wherein the compression member includes a tie memberor a series of tie members which anchor the intraluminal stent to thecatheter and prevent the intraluminal stent moving from its firstcompressed state to its second expanded state.
 87. The delivery systemof claim 86 wherein the tie member(s) are sutures which have apre-determined breaking strength.
 88. The delivery system of claim 83wherein the compression member comprises one or more of a collar, ringor spiral wrap or combinations thereof around the intraluminal stent.89. The delivery system of claim 83 wherein the release member comprisesa balloon member positioned along the length of the elongate body of thecatheter.
 90. The delivery system of claim 89 wherein the balloon memberis substantially surrounded by the intraluminal stent.
 91. The deliverysystem of claim 89 wherein movement of the balloon member from a firstdeflated state to a second inflated state releases the compressive forceof the compression member.
 92. The delivery system of claim 91 whereinsaid membrane has at least one frangible region such that when theballoon member moves from its deflated to inflated state, said at leastone frangible region is broken and the intraluminal stent is allowed tomove to its second radially expanded state.
 93. The delivery system ofclaim 92 wherein said frangible region comprises one or moreperforations in the body of the membrane.
 94. The delivery system ofclaim 83 wherein the intraluminal stent is a self expanding stent. 95.The delivery system of claim 83 wherein the compression member is amembrane around the intraluminal stent, said membrane having at least afrangible region along at least a portion of its length, and saidrelease member is a pull suture which is aligned with and/or threadedthrough the frangible region of the membrane.
 96. The delivery system ofclaim 95 wherein the pull suture extends to a location outside the bodysuch that when the intraluminal stent is in position at a target site,the pull suture is movable in a direction towards the proximal end ofthe intraluminal stent such that the frangible region is broken and thecompressive force of the membrane released from the intraluminal stentwhich may then move to its radially expanded state.
 97. The deliverysystem of claim 83 wherein the compression member is an expandablemembrane.
 98. The delivery system of claim 97 wherein the membrane issealed around the stent.
 99. The delivery system of claim 98 wherein therelease member comprises a fluid that can be delivered to the sealedmembrane and so expand the membrane.
 100. The delivery system of claim99 wherein the fluid is delivered into the sealed membrane by thecatheter through apertures therein.
 101. The delivery system of claim100 wherein the membrane breaks into one or more portions on undergoinga predetermined degree of expansion.
 102. The delivery system of claim98 wherein the membrane contains or includes one or more pharmaceuticalagents.
 103. The delivery system of claim 102 wherein the membranecomprises a reservoir member to hold one or more pharmaceutical agentstherewithin.
 104. A delivery system for the delivery of an intraluminalstent to a target vessel, said delivery system comprising an introducercatheter having an elongate tubular body to allow the passagetherethrough of a placement catheter, said placement catheter having anelongate body which extends from a proximal end to a distal end andwhich carries the intraluminal stent at a position intermediate saidproximal end and said distal end; the delivery system further includinga membrane around the intraluminal stent said membrane holding theintraluminal stent in a radially compressed configuration and whereinsaid membrane comprises a first section and a second section, said firstand second sections demarcated by a region of weakness in the membrane.